Prostate-specific membrane antigen Radioguided Surgery to Detect Nodal Metastases in Primary Prostate Cancer Patients Undergoing Robot-assisted Radical Prostatectomy and Extended Pelvic Lymph Node Dissection: Results of a Planned Interim Analysis of a Prospective Phase 2 Study
Authors: Giorgio Gandaglia, Elio Mazzone, Armando Stabile, Antony Pellegrino, Vito Cucchiara, Francesco Barletta, Simone Scuderi, Daniele Robesti, Riccardo Leni, Ana Maria Samanes Gajate, Maria Picchio, Luigi Gianolli, Giorgio Brembilla, Francesco De Cobelli, Matthias N. van Oosterom, Fijs W.B. van Leeuwen, Francesco Montorsi, Alberto Briganti
Journal: European Urology (2022)

Extended pelvic nodal dissection (ePLND) represents the gold standard for nodal staging in prostate cancer (PCa). Prostate-specific membrane antigen (PSMA) radioguided surgery (RGS) could identify lymph node invasion (LNI) during robot-assisted radical prostatectomy (RARP). To report the planned interim analyses of a phase 2 prospective study (NCT04832958) aimed at describing PSMA-RGS during RARP. A phase 2 trial aimed at enrolling 100 patients with intermediate- or high-risk cN0cM0 PCa at conventional imaging with a risk of LNI of >5% was conducted. Overall, 18 patients were enrolled between June 2021 and March 2022. Among them, 12 patients underwent PSMA-RGS and represented the study cohort. All patients received 68Ga-PSMA positron emission tomography (PET)/magnetic resonance imaging; 99mTc-PSMA-I&S was synthesised and administered intravenously the day before surgery, followed by single-photon emission computed tomography/computed tomography. A Drop-In gamma probe was used for in vivo measurements. All positive lesions (count rate ≥2 compared with background) were excised and ePLND was performed. Side effects, perioperative outcomes, and performance characteristics of robot-assisted PSMA-RGS for LNI were measured. Overall, four (33%), six (50%), and two (17%) patients had intermediate-risk, high-risk, and locally advanced PCa. Overall, two (17%) patients had pathologic nodal uptake at PSMA PET. The median operative time, blood loss, and length of stay were 230 min, 100 ml, and 5 d, respectively. No adverse events and intraoperative complications were recorded. One patient experienced a 30-d complication (Clavien-Dindo 2; 8.3%). Overall, three (25%) patients had LNI at ePLND. At per-region analyses on 96 nodal areas, sensitivity, specificity, positive predictive value, and negative predictive value of PSMA-RGS were 63%, 99%, 83%, and 96%, respectively. On a per-patient level, sensitivity, specificity, positive predictive value, and negative predictive values of PSMA-RGS were 67%, 100%, 100%, and 90%, respectively. Robot-assisted PSMA-RGS in primary staging is a safe and feasible procedure characterised by acceptable specificity but suboptimal sensitivity, missing micrometastatic nodal disease. Prostate-specific membrane antigen radioguided robot-assisted surgery is a safe and feasible procedure for the intraoperative identification of nodal metastases in cN0cM0 prostate cancer patients undergoing robot-assisted radical prostatectomy with extended pelvic lymph node dissection. However, this approach might still miss micrometastatic nodal dissemination.